A optical device includes: a display device configured to output a display image; a lens on one side of the display device; and a polarization control unit between the display device and the lens and configured to output the display image output from the display device as first polarized light or second polarized light, wherein the lens comprises: a first polarizing mirror configured to reflect a display image of the first polarized light and to transmit a display image of the second polarized light; and a second polarizing mirror configured to reflect a display image of the second polarized light and to transmit a display image of the first polarized light.